This past November, the UNEP released the 2014 edition of their annual "Emissions Gap Report," which highlighted the important role that carbon dioxide removal ("CDR") solutions are likely to play in preventing climate change. In particular, the UNEP report finds that the global economy has come precariously close to going "over-budget" on CO2 emissions -- that is, humans are on track to emit more CO2 into the atmosphere than the planet can handle without warming significantly. If we do overshoot our carbon "budget" in the next several decades, the only way to return atmospheric CO2 concentrations to levels that avoid climate change will be to deploy large-scale CDR projects capable of generating net "negative" emissions:
Above: the blue-shaded regions of the graphs from the UNEP Emissions Gap Report 2014 show that we are on track to overshoot the "budget" of carbon we can emit into the atmosphere without triggering significant climate change. The only way to reduce CO2 levels back under "budget" in these scenarios is to deploy large-scale CDR projects (orange-shaded regions).
The UNEP report notes a large caveat associated with these overshoot scenarios, namely that:
"although scenarios routinely assume a substantial amount of global negative emissions, the feasibility of these assumptions still needs to be explored."
To put this another way, many overshoot scenarios assume large-scale CDR deployments, but we currently do not have any CDR technologies that are proven in their ability to remove large amounts of CO2 from the atmosphere.
In many regards, planning to overshoot our carbon budget before developing scaleable CDR solutions is like planning to jump out of a plane before learning how to work a parachute: it is possible to figure out how to operate a parachute on the way down, but it is much more prudent to jump only after learning how to operate it.
And the UNEP report repeatedly advises readers of the benefits of avoiding overshoot scenarios if possible:
"taking more action now [to reduce GHG emissions] reduces the need for taking more extreme action later to stay within the 2 °C limit."
"the quicker emissions are reduced now, the less society will be dependent on negative emissions later"
But the UNEP report also shows that most of the world's governments are ignoring this advice, and are failing to plan for large enough emission reductions to prevent climate change without overshooting carbon budgets:
Above: the projected emissions gap in 2030 in the UNEP report shows that countries are not planning to make the necessary GHG emissions reductions to avoid overshooting our carbon "budget", meaning that large-scale CDR would be necessary to fill the gap and prevent climate change.
So with our carbon "budget" rapidly dwindling, it is increasingly clear that now is the time to accelerate both GHG emissions reduction activities and research and development of CDR solutions. In other words, we are about to reach the edge of our carbon budget, so we have no time to lose in developing a "CDR parachute..."